Systems and methods for initiating annular obstruction in a subsurface well

ABSTRACT

The present invention is directed to systems and methods for initiating annular obstructions in wells used in, or in support of, enhanced oil recovery operations—particularly enhanced oil recovery (EOR) efforts involving steam injection (e.g., steam flooding). In at least some instances, system and method embodiments of the present invention utilize one or more passively-activated annular obstruction devices (and/or hybrid active/passive devices) for inducing annular obstruction, wherein the associated passive or hybrid activation is at least partially controlled by thermal means such that it can be deemed to be thermally-directed or thermally-controlled. Such thermally-directed passive activation can afford considerably more control over the annular obstruction process and, correspondingly, over the overall steam injection into the formation and associated reservoir—thereby providing more efficient recovery of hydrocarbons.

FIELD OF THE INVENTION

This invention relates generally to oilfield drilling and completionoperations, and specifically to systems and methods for initiatingannular obstructions in wells used in, or in support of, suchoperations—particularly enhanced oil recovery operations such as thosethat involve steam flooding.

BACKGROUND

Steam flooding is a common method for producing oil from reservoirs thatwould otherwise be difficult to produce from using conventionalresources. This type of enhanced oil recovery (EOR) technique typicallyutilizes a plurality of steam injection wells interspersed withproduction wells. See, e.g., Hutchison et al., U.S. Pat. No. 4,099,563,issued Jul. 11, 1978; and Shu, U.S. Pat. No. 4,431,056, issued Feb. 14,1984.

Steam injection wells are often partially cased down close to the regionin which steam is to be injected. The region of the well where steam isto be injected, however, must remain open to the formation comprisingthe target reservoir. In this region, a liner string is typically runsome distance (e.g., several hundred to several thousand meters), withslots, holes, or other porous channels permitting fluid communicationwith the formation along at least portions of the length of linerstring. See, e.g., Themig, U.S. Pat. No. 4,942,925, issued Jul. 24,1990.

Ideally, during steam injection, an even flux of fluid to the reservoiris maintained. In practice, however, unrestricted flow in the annulus,complicated by reservoir heterogeneities and/or varying reservoirpressures, results in an uneven flow of fluid to the reservoir. In turn,this uneven flux or flow of fluid to the formation reduces overallhydrocarbon extraction yields from the reservoir.

A number of devices are currently employed in the industry to ensure afairly even flux of fluid out of the liner and into the formation. Suchdevices generally induce an annular obstruction (i.e., a barrier) withinthe annular region (see, e.g., Grigsby et al., U.S. Pat. No. 6,564,870,issued May 20, 2003). In some instances, such devices are activelydeployed such that specific actions are taken to actuate and/or activatethe obstruction (e.g., hydraulic and/or mechanical actuation). Thedownside to such devices, and their method of deployment, is the need torun mechanical and/or hydraulic actuation means downhole.

In other instances, the activation of such above-mentioned devices ispassive—requiring no direct external intervention, e.g., a “swellpacker” that comprises a mandrel wrapped in an elastomeric material,wherein the elastomeric material swells in the presence of a particularfluid that is introduced into the annular region.

In view of the foregoing, an improved method and/or system for passivelyobstructing the annular region (or a passive obstruction comprisingactive elements, e.g., a hybrid obstruction) in a steam injection wellwould be extremely useful—particularly wherein such a method and/orsystem provides better control over the actuation process without havingto run tools or devices downhole to mechanically and/or hydraulicallyactuate an annular obstruction packer.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is directed to systems and methods for initiatingannular obstructions in wells used in, or in support of, enhanced oilrecovery operations—particularly enhanced oil recovery (EOR) effortsinvolving steam injection (e.g., steam flooding). In at least someinstances, system and method embodiments of the present inventionutilize one or more passively-activated annular obstruction devices(and/or hybrid active/passive devices) for inducing annular obstruction,wherein the associated passive or hybrid activation is at leastpartially controlled by thermal means such that it can be deemed to bethermally-directed or thermally-controlled. Such thermally-directedpassive activation can afford considerably more control over the annularobstruction process and, correspondingly, over the overall steaminjection into the formation and associated reservoir—thereby providingmore efficient recovery of hydrocarbons.

In some embodiments, the present invention is directed to one or moresystems of a first type for initiating annular obstruction in asubsurface (e.g., steam injection) well, such one or more systems of afirst type generally comprising: (a) an at least partially permeableliner string situated within a portion of a wellbore that is at leastpartially open to a hydrocarbon-bearing formation; (b) a sealed metalchamber disposed about a portion of the at least partially permeableliner string; (c) a material contained within the sealed metal chamber,wherein said material is initially in a condensed state, but whichtransitions to a gaseous state when heated above a certain thresholdtemperature; and (d) a means of heating the material contained withinthe metal chamber so as to effect its transition to the gaseous statewhere, upon transitioning to a gas, the material increases the pressurewithin the chamber, and where, upon experiencing a pressure increase,the metal chamber expands in such a way as to engage the formation,thereby forming an annular obstruction between the at least partiallypermeable liner string and the formation. Such system embodiments of afirst type can be seen as comprising a chamber-based annular obstructiondevice (or means), i.e., that part of the partially permeable linerstring that is functionally operable for engaging the formation wall andeffecting annular obstruction in at least a region of the wellboreannulus.

In some embodiments, the present invention is directed to one or moremethods of a first type for initiating annular obstruction in asubsurface (e.g., steam injection) well, such one or more methods of afirst type generally comprising the steps of: (a) fabricating a modifiedlength of at least partially permeable liner string, the modified lengthcomprising: (i) a sealed metal chamber disposed about the modifiedlength of at least partially permeable liner string; and (ii) a materialsituated inside the sealed metal chamber, wherein said material isinitially in a condensed state and which transitions to a gas whenheated above a certain threshold temperature; (b) positioning themodified length of at least partially permeable liner string in an atleast partially open hole region of a wellbore, wherein an annularregion is established between the modified length of permeable linerstring and the open hole region of the wellbore; and (c) heating themodified length of liner string so as to effect a transition of thematerial contained therein from a condensed state to a gaseous state,where upon transitioning to a gas, the material increases the pressurewithin the sealed metal chamber, and where upon experiencing a pressureincrease the sealed metal chamber expands in such a way as to engage theformation, thereby forming an annular obstruction between the modifiedlength of liner string and the formation. In a manner analogous to thecorresponding systems (of a first type) mentioned above, the modifiedlength of partially permeable liner string can be seen to comprise achamber-based annular obstruction device.

In some embodiments, the present invention is directed to one or moresystems of a second type for initiating annular obstruction in asubsurface well, each of said one or more systems generally comprising:(a) an at least partially permeable liner string situated within aportion of a wellbore that is at least partially open to ahydrocarbon-bearing formation; (b) a load-bearing coiled spring disposedabout a portion of the at least partially permeable liner string,wherein the load-bearing coiled spring is in a load-bearing stateselected from the group consisting of a tensioned state and a compressedstate; (c) a spring retainer device attached to the load-bearing coiledspring so as to maintain it in a load-bearing state, wherein the springretainer device is at least partially fabricated of material designed tomelt above a predetermined temperature, and wherein upon melting losesits ability to maintain the coiled spring in a load-bearing state; and(d) metal mesh functionally-associated (e.g., interposed) with theload-bearing spring such that removal of the load from the spring causesthe metal mesh to engage the formation, thereby forming an annularobstruction between the liner string and the formation, wherein the loadremoval is effected by application of heat to the annular regionsufficient to melt at least a portion of the spring retainer device.Such systems of a second type can be seen as comprising a coiledspring-based annular obstruction device or means, wherein such a deviceis comprised of a load-bearing coiled spring, metal mesh, and retainerpin(s), that collectively function to engage the formation (therebyinducing obstruction) when actuated.

In some embodiments, the present invention is directed to one or moremethods of a second type for initiating annular obstruction in asubsurface well, said methods generally comprising the steps of: (a)fabricating an at least partially permeable length of modified linerstring, the length of modified liner string comprising: (i) aload-bearing coiled spring disposed about at least a portion of themodified liner string, wherein the load-bearing coiled spring is in aload-bearing state selected from the group consisting of a tensionedstate and a compressed state; (ii) a spring retainer device attached tothe load-bearing coiled spring so as to maintain it in the load-bearingstate, wherein the spring retainer device is at least partiallyfabricated of material designed to melt above a predeterminedtemperature, and wherein upon melting loses its ability to maintain thecoiled spring in a load-bearing state; and (iii) metal meshfunctionally-associated with the load-bearing coiled spring such thatwhen the coiled spring undergoes a transformation from a load-bearingstate to a non-load-bearing state, the metal mesh expands outward in aradial direction; (b) positioning the at least partially permeablelength of modified liner string in an open hole region of a wellbore,wherein an annular region is established between the modified length ofliner string and the open hole region of the wellbore; and (c) heatingthe modified length of liner string so as to melt the spring retainerdevice and effect the transformation of the coiled spring to thenon-load-bearing state, correspondingly causing the metal mesh to expandoutwardly and engage the formation, thereby forming an annularobstruction between the modified length of liner string and the openhole. In a manner analogous to the corresponding systems (of a secondtype) mentioned above, the modified length of partially permeable linerstring can be seen to comprise a coiled spring-based annular obstructiondevice.

The foregoing has outlined rather broadly the features of the presentinvention in order that the detailed description of the invention thatfollows may be better understood. Additional features and advantages ofthe invention will be described hereinafter which form the subject ofthe claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 is an illustrative overview of how systems of the presentinvention can be configured, wherein the number and placement of theindividual components of such systems is meant merely to beillustrative, not limiting;

FIG. 2A depicts a sealed metal chamber, in its unexpanded state,disposed about a portion of a liner joint, where the chamber isconstructed so as to be an integral part of the liner joint, inaccordance with some embodiments of the present invention;

FIG. 2B depicts the sealed metal chamber of FIG. 2A, but in its expandedstate, as a result of the material contained within transitioning from acondensed state to a gaseous state, in accordance with some embodimentsof the present invention;

FIG. 3A depicts a sealed metal chamber, in its unexpanded state,disposed about a portion of a liner joint in a manner such that it isnot an integral part of the liner joint, in accordance with someembodiments of the present invention;

FIG. 3B depicts the sealed metal chamber of FIG. 3A, but in its expandedstate, as a result of the material contained within transitioning from acondensed state to a gaseous state, in accordance with some embodimentsof the present invention;

FIG. 4 outlines, in flow diagram form, methods of a first type forinitiating annular obstruction in a subsurface well, in accordance withsome embodiments of the present invention;

FIG. 5A depicts an annular obstruction means for use in some system andmethod embodiments (of a second type) of the present invention, whereinthe load-bearing coiled spring, about which metal mesh is interposed, isin a tensioned or expanded state;

FIG. 5B depicts the obstruction means of FIG. 5A, but in itsnon-load-bearing state, where the metal mesh interposed therewith hasexpanded so as to engage the formation and thereby impart annularobstruction;

FIG. 6A depicts an annular obstruction means for use in some system andmethod embodiments (also of a second type) of the present invention,wherein the load-bearing coiled spring, functionally-associated with anetwork of metal mesh, is in a compressed state;

FIG. 6B depicts the obstruction means of FIG. 6A, but in itsnon-load-bearing state, where the metal mesh functionally-associatedwith the coiled spring has expanded so as to engage the formation andthereby impart annular obstruction; and

FIG. 7 outlines, in flow diagram form, methods of a second type forinitiating annular obstruction in a subsurface well, in accordance withsome embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION 1. Introduction

This invention is directed to systems and methods for initiating annularobstructions in wells used in, or in support of, enhanced oil recoveryoperations—particularly enhanced oil recovery involving steam flooding.In at least some instances, system and method embodiments of the presentinvention utilize one or more passively-activated devices (or means) forinducing annular obstruction, wherein the associated passive activationis thermally-directed. In contrast to the passive activation devices andtechniques referred to in the background section (vide supra), suchthermally-directed passive activation can afford considerably morecontrol over the annular obstruction process and, correspondingly, overthe overall steam injection into the formation and associated reservoir.

Mechanisms by which the systems and methods of the present inventionthermally-direct such passive actuation of annular obstruction will beelaborated on more fully below. In a general sense, however, all of suchsystems and methods rely on one or more thermally-activated obstructivedevices. The relation of such devices to other components of asteam-injection well are illustrated, in exemplary fashion, in FIG. 1,wherein the well is depicted as a deviated well, but this need not bethe case in every situation.

With reference now to FIG. 1, in a subsurface well 110 extending downfrom surface 121, an open hole region 184 extends from a cased region174, wherein the cased region in established by casing string 114 thatis typically cemented in place. Within the well, a liner string 120extends from the cased region into, and largely through, the open holeregion, wherein the liner string 120 is (typically) functionallyconnected to the casing string 114 via the use of a liner hanger orpacker 118 (or, generally, one or more annular obstruction devices).Along portions of the length of liner string 120 (comprised of numeroussegments of liner joints) are one or more regions of pores (e.g., 128and 142) from which fluid (e.g., steam) can emanate, filling the annularregions 122 and 136 established between the liner string 120 and theformation wall 123, and accessing reservoirs contained within regions135 and 155 of the surrounding formation. By careful placement andpassive actuation of annular obstruction-inducing devices 124, 126, 130,and 134 (shown in the expanded state), the flow of steam (or otherfluid) to the formation can be carefully controlled. Note that thenumber and relative placement of the devices is meant merely to beillustrative, and not meant to limit the scope of the invention.

In some embodiments or instances, the means or devices for inducingannular obstruction can (e.g., as part of, or used in, systems andmethods of the present invention) generally fall into one of twocategories depending upon the type of mechanism and/or operation theyemploy. In some instances, the mechanism and/or operation is based on atemperature-actuated expanding metal chamber (e.g., systems and methodsof a first type). In other instances, the mechanism and/or operation isbased on a load-bearing coiled spring (e.g., systems and methods of asecond type).

With regard to the active/passive nature of actuation/activationmentioned above, in some such above-described embodiments the mechanismsand/or means by which the systems and/or methods operate to induceannular obstructions can be deemed to be hybrid mechanisms and/or meansby which thermal direction (vide supra) can afford some measure ofactive activation or actuation.

2. Definitions

Certain terms are defined throughout this description as they are firstused, while certain other terms used in this description are definedbelow:

A “liner string,” as defined herein, is similar to a casing string inthat it is made up of joints (pipe segments threaded on each end), butit is not run to the well surface as a casing string is. Instead, aliner string is suspended by a liner hanger attached to the casing aboveit. For open-hole wells, the liner string is not cemented and is influid communication with the formation.

An “open-hole well,” as defined herein, is a well in which liner stringis in direct fluid communication with the formation. Often, such wellsare cased (and cemented) down to the source/reservoir rock.

An “annulus,” as defined herein, refers to the volume or void spacebetween two essentially cylindrical objects. As an example, in an openhole wellbore, the space between the liner string and formation wall isdeemed an annulus.

An “annular region,” as defined herein, refers to a portion of anannulus, wherein such a portion can be physically or conceptuallyisolated from the remainder of the annulus of which it is a part.

The term “annular obstruction,” as defined and used herein, refers tofluid-flow restriction in one or more (annular) regions of a wellboreannulus.

The term “active actuation,” as defined herein, describes the process bywhich a device is actively actuated or activated by direct applicationof some form of hydromechanical work.

The term “passive actuation,” as defined herein, describes the processby which a device is actuated by its passive exposure to anenvironmental condition.

The term, “hybrid actuation,” as defined herein, describes the processby which a device is actuated by an environmental condition that isactively or deliberately altered.

“Steam injection,” as defined herein; is the injection ofsurface-generated steam into a subsurface formation, typically to aidthe recovery of hydrocarbonaceous assets therein.

“Steam flooding,” as defined herein, is an enhanced oil recovery (EOR)technique that employs steam injection to render oil more amenable toflow (out of the reservoir). Typically, this involves multiple steaminjection wells to be employed simultaneously.

3. Systems of a First Type

As mentioned previously herein (vide supra), systems and methods of thepresent invention, for initiating annular obstruction in subsurfacewells, can be broadly categorized into one of two types—depending on thetype of mechanism by which annular obstruction is actuated or otherwiseinitiated. The discussion that follows, within this section, is directedat systems (i.e., systems of a first type) that employ a mechanism thatis based, in large part, on the expansion of a sealed metal chamber.Such systems can be seen to comprise one or more chamber-based annularobstruction devices (vide infra).

With reference to FIGS. 2A and 2B, and with continued reference to FIG.1 (for exemplary system component correlation), in some embodiments, thepresent invention is directed to a system (or systems) for initiatingannular obstruction in a subsurface well 110, said system comprising:(a) an at least partially permeable liner string 120 situated within aportion of a wellbore (of subsurface well 110) that is at leastpartially open to a hydrocarbon-bearing formation (e.g., region 184);(b) a sealed metal chamber (e.g., as in 210 and/or 310) disposed about aportion of the at least partially permeable liner string 120; (c) amaterial contained within the sealed metal chamber, wherein saidmaterial is initially in a condensed state (e.g., 215 and/or 315), butwhich transitions to a gaseous state (e.g., 217 and/or 317) when heatedabove a certain threshold temperature; and (d) a means of heating thematerial contained within the metal chamber so as to effect itstransition to the gaseous state where, upon transitioning to a gas, thematerial increases the pressure within the chamber, and where, uponexperiencing a pressure increase, the metal chamber expands in such away as to engage the formation, thereby forming an annular obstruction(e.g., 124, 126, 130, 134) between the at least partially permeableliner string 120 and the formation (i.e., formation wall 123).

In some such above-described system embodiments, the subsurface well 110is a steam injection well. While such systems are directed to generatingannular obstruction/isolation in subsurface wells in general, steaminjection is an economical and efficient method for additionally serving(in addition to its primary enhanced oil recovery purpose) as a means ofheating, capable of effecting the transition of the material containedwithin the sealed metal chamber from a condensed state (e.g., material215 and/or 315) to a gaseous state (e.g., material 217 and/or 317) (videinfra).

In some such above-described system embodiments, the well 110 is adeviated well, or at least includes sections that deviate from avertical orientation (relative to the surface). The well of FIG. 1,i.e., subsurface well 110, is depicted as a deviated well, wherein asignificant portion of the open hole region of the well runs in asubstantially horizontal (e.g., greater than 45° deviation fromvertical) direction through much of the formation.

In some such above-described system embodiments, the at least partiallypermeable liner string comprises pores or openings of a type selectedfrom the group consisting of pre-drilled holes, slots, screens, andcombinations thereof. In FIG. 1, exemplary liner string 120 comprisespores 128, 142 depicted as pre-drilled holes.

In some such above-described system embodiments, the sealed metalchamber is an integral part of the liner pipe (e.g., segment or joint ofliner string 120) making up at least part of the at least partiallypermeable liner string. System embodiments such as these are depicted inFIGS. 2A and 2B, wherein it can be seen that the exterior wall of theliner joint 202 forms part of the sealed metal chamber 210. As aconsequence, the material inside the chamber is in direct contact withthe outer wall of the liner string. Those of skill in the art willrecognize that numerous methods exist for forming such a sealed metalchamber that is an integral part of the liner pipe, wherein such methodscan include welding techniques.

In some such above-described system embodiments, the sealed metalchamber is an attachment affixed to the at least partially permeableliner string. System embodiments such as these are depicted in FIGS. 3Aand 3B, wherein it is seen that the sealed metal chamber 310 comprisesits own wall 311 that shields the liner pipe 202 from the material (315,317) contained within the sealed metal chamber. Similar to theembodiments above (i.e., those depicted in FIGS. 2A and 2B), chamberelement 311 can be welded or otherwise affixed to the rest of sealedmetal chamber 310. Sealed metal chamber 310 can be slid onto the linerpipe 202 before the pipe is deployed in the well, and the sealed metalchamber can be welded, affixed, or made to otherwise adhere to the linerpipe 202 by one or more of a variety of techniques known to those ofskill in the art.

In some such above-described system embodiments, the sealed metalchamber (210, 310) has a geometry configured to enhance its ability toengage the formation (i.e., wall 123) upon expanding. Such enhancedgeometrical configurations can take a variety of forms including, butnot limited to, corrugations, ridges, undulations, and the like.Generally, however, such geometrical configuration enhancements aredesigned to permit better engagement of the formation wall uponexpansion.

In some such above-described system embodiments, the above mentionedsealed metal chamber (210, 310) comprises at least one relief valvedesigned to vent below the burst pressure of said chamber. Such reliefvalves are known in the art in terms of their form and function, and itis within the purview of those skilled in the art to functionallyintegrate one or more of such valves into the design of one or more ofthe above-mentioned sealed metal chambers.

In some such above-described system embodiments, the sealed metalchamber (210, 310) typically comprises a volume, in the unexpandedstate, of from at least about 50 cubic inches (0.8 L) to at most about1,200 cubic inches (19.7 L). In some other such above-described systemembodiments, the sealed metal chamber typically comprises a volume, inthe unexpanded state, of from at least about 800 cubic inches (13.1 L)to at most about 3,000 cubic inches (49.2 L). In some still other suchabove-described system embodiments, the sealed metal chamber typicallycomprise a volume, in the unexpanded state, of from at least about 2,800cubic inches (45.9 L) to at most about 12,000 cubic inches (196.7 L).

In some such above-described system embodiments, the material (e.g.,215, 315) inside the sealed metal chamber, upon transitioning to agaseous state (e.g., 217, 317), increases the volume of the sealed metalchamber (e.g., the chamber transitioning from 210 to 212 and/or 310 to312) typically by at least about 50 percent; in some or other suchembodiments, typically by at least 100 percent; and in some or stillother embodiments, typically by at least 200 percent. Upper limits onsuch expansion are typically about 300 percent.

Depending on the embodiment, the material (e.g., 215, 315) inside thesealed metal chamber can be placed inside the chamber during the chambermanufacture, or afterwards via a valve or other re-sealable access port.In some such above-described system embodiments, the material inside thesealed metal chamber is, in its condensed state, in a form selected fromthe group consisting of liquid, solid, and any mixture thereof. In somesuch system embodiments, the material inside the sealed metal chamber isselected from the group consisting of water, alcohols, glycols,glycerin, phase change materials (PCMs), eutectics, and combinationsthereof. Note that in some embodiments, in instances where the condensedmaterial is a solid, the solid can undergo a direct transition to thegaseous state (i.e., sublimation, upon being heated).

In some such above-described system embodiments (of a first type), suchsystems can be seen as comprising a chamber-based annular obstructiondevice/means (or a plurality thereof), i.e., that part of the partiallypermeable liner string that is functionally operable for engaging theformation wall and effecting annular obstruction in at least a region ofthe wellbore annulus. Such a device or means would correspond, inexemplary fashion, with one or more of annular obstruction devices 124,126, 130, and 134, as depicted in FIG. 1.

In some such above-described system embodiments, the annular obstructionreduces flow in the annulus by at least about 20 percent to at mostabout 100 percent. In some other such embodiments, the annularobstruction reduces flow in the annulus by at least about 20 percent toat most about 90 percent. In some or still other embodiments, theannular obstruction reduces flow in the annulus by at least about 40percent to at most about 90 percent.

In some such above-described system embodiments, the means of heatingthe condensed material comprises introduction of a downhole heat source;i.e., the thermal energy needed to effect the phase transition of the(initially) condensed material inside the sealed metal chamber isgenerated in the well, below the surface. Downhole heat sources areknown in the art and include, but are not limited to, downhole resistiveheaters, microwave heaters, and chemical (e.g., exothermic) reactions.See, e.g., MacSporran, U.S. Pat. No. 3,072,189, issued Jan. 8, 1963.

In some such above-described system embodiments, the means of heatinginvolves injection of a heated fluid into the well, i.e., heating afluid at the surface and then injecting it into the well. In some suchembodiments, the means of heating the condensed material involves theinjection of steam into the well. Means of heating suitable such fluidsat the surface are known in the art, as are methods of introducing sucha heated fluid into a wellbore. Means also exist for additionally oralternatively heating the fluid downhole. Regardless of whether theheating is carried out at the surface or downhole, in some embodiments,the means of heating the condensed fluid makes use of an exothermicchemical reaction.

In some such above-described system embodiments, such systems furthercomprise one or more additional sealed metal chambers filled with thecondensed material, so as to effect multiple annular obstructions in thewellbore. Such an embodiment may be seen to be illustrated in FIG. 1,wherein four such annular obstruction devices (i.e., chamber-baseddevices comprising sealed metal chambers) are depicted in the figure asdevices 124, 126, 130, and 134.

4. Methods of a First Type

Method embodiments (of a first type) described in this section generallycorrespond in a substantial manner with the system embodiments (of afirst type) described above in Section 3. Accordingly, reference willcontinue to be made, in exemplary fashion, to FIGS. 1, 2A, 2B, 3A, and3B, as many of the details are common to both the system and methodembodiments.

Referring now to FIG. 4, in some embodiments the present invention isdirected to one or more methods for initiating annular obstruction in asubsurface well, said method(s) comprising the steps of: (Step 401)fabricating a modified length of at least partially permeable linerstring, the modified length comprising: (i) a sealed metal chamberdisposed about the modified length of at least partially permeable linerstring; and (ii) a material situated inside the sealed metal chamber,wherein said material is initially in a condensed state and whichtransitions to a gas when heated above a certain threshold temperature;(Step 402) positioning the modified length of at least partiallypermeable liner string in an at least partially open hole region of awellbore, wherein an annular region is established between the modifiedlength of permeable liner string and the open hole region of thewellbore; and (Step 403) heating the modified length of liner string soas to effect a transition of the material contained therein from acondensed state to a gaseous state, where upon transitioning to a gas,the material increases the pressure within the sealed metal chamber, andwhere upon experiencing a pressure increase the sealed metal chamberexpands in such a way as to engage the formation, thereby forming anannular obstruction between the modified length of liner string and theformation.

Like the system embodiments (of a first type) described above, thefunctional components described above in relation to the systemembodiments, being operable for engaging the formation and inducingannular obstruction, can be deemed (at least in some embodiments) to bechamber-based annular obstruction devices (vide supra).

As in the case of the analogous system embodiment described above, insome such above-described method embodiments, the subsurface well is asteam injection well. In some such embodiments, the steam injected intothe subsurface (in an effort to enhance oil recovery) can further serveas a means by which the modified length of liner string can be heated soas to effect a transition of the material contained therein from acondensed state to a gaseous state (vide infra).

Corresponding to the analogous system embodiments above, in some suchabove-described method embodiments, the subsurface well is a deviatedwell. Generally speaking, a well is deemed to be “deviated” if asubstantial part of the wellbore deviates from a vertical axisestablished with the surface. Note that such deviation is typicallyintentional (e.g., directional drilling); and while some such subsurfacewells so formed are largely horizontal (common for steam injectionwells), the wells used in conjunction with at least some methods and/orsystem embodiments of the present invention are not required to be ofthe deviated variety.

In some such above-described method embodiments, and in at least somemeasure of correspondency with the analogous system embodiments (of afirst type) described above, the at least partially permeable linerstring comprises pores (openings, orifices) of a type selected from thegroup consisting of pre-drilled holes, slots, screens, and combinationsthereof. Characteristics and variation among such pores is as describedabove in the analogous system embodiments.

In a manner similar to that described for the system embodiments (of afirst type) in Section 3 above, the sealed metal chamber can be eitheran integral part of the modified length of liner pipe making up the atleast partially permeable liner string (e.g., as in FIGS. 2A and 2B), orit can be an attachment affixed to the at least partially permeableliner string (e.g., as in FIGS. 3A and 3B).

In analogous correspondence to one or more of the system embodiments (ofa first type) described above, in some such above-described methodembodiments, the sealed metal chamber has a geometry configured so as toenhance its ability to engage the formation upon expanding. Accordingly,in some such embodiments, efficient expansion is designed and/orengineered into the sealed metal chamber by way of its geometry and/orassociated geometrical features.

In some such above-described method embodiments, the sealed metalchamber comprises at least one relief valve designed to vent below theburst pressure of said chamber. In some such embodiments, while perhapsserving in a rupture-prevention capacity, such relief valves mayadditionally or alternatively be designed to vent in such a way as tocontrol the pressure and fluid flow in the annular region.

As in the case of some such analogous system embodiments, in some suchabove-described method embodiments, the sealed metal chamber comprises avolume, in the unexpanded state, of from at least about 50 cubic inches(0.8 L) to at most about 12,000 cubic inches (196.7 L). In some or othersuch method embodiments, the sealed metal chamber, upon transitioning toa gaseous state, increases the volume of the sealed metal chamber by atleast about 50 percent.

In some such above-described method embodiments, the material situatedinside the sealed metal chamber is, in its condensed state, in a formselected from the group consisting of liquid, solid, and any mixturethereof. In some such method embodiments, the material situated insidethe sealed metal chamber is selected from the group consisting of water,alcohols, glycols, glycerin, phase change materials, eutectics, andcombinations thereof.

In some such above-described method embodiments, the annular obstructionreduces flow in at least some regions of the annulus from at least about20 percent to at most about 100 percent, i.e., complete annularobstruction or isolation for one or more annular regions. In some orother such embodiments, the annular obstruction reduces flow in suchannular regions from at least about 40 percent to at most about 100percent.

In some such above-described method embodiments, the means of heatingthe condensed material involves injection of a heated fluid into thewell. This fluid may be heated at the surface prior to injection, and/orit can be additionally or alternatively heated subsurface via one ormore of a variety of subsurface heating means. Additional heatingsubsurface, with strategically-positioned heaters or other heatingmeans, can impart additional control over the temporal actuation of theannular obstruction device(s). As mentioned above, particularly for thecase of steam injection wells used for enhanced oil recovery, in somesuch method embodiments the means of heating the condensed materialinvolves injecting steam into the well.

In some such above-described method embodiments, the means of heatingthe condensed fluid makes use of conventional heating means known topersons skilled in the art. In some or other method embodiments, suchheating means an additionally or alternatively make use of radiativeheating means (e.g., microwave or radiofrequency (RF) heating) and/orchemical heating means (e.g., an exothermic chemical reaction).

In some such above-described method embodiments, such methods furthercomprise the use of multiple modified lengths of at least partiallypermeable liner string, so as to effect multiple annular obstructions inmultiple regions of the wellbore. An exemplary such embodiment is shownin FIG. 1, where four such annular obstruction devices (124, 126, 130,and 134) are shown.

5. Systems of a Second Type

As mentioned previously herein, systems and methods of the presentinvention, for initiating annular obstruction in subsurface wells, canbe broadly categorized into one of two types—depending on the type ofmechanism by which annular obstruction is actuated or otherwiseinitiated. The discussion that follows, i.e., the discussion within thissection, is directed at systems (i.e., systems of a second type) thatemploy a mechanism that is based, in large part, on the expansion of ametal mesh material that is functionally-associated with a coiled springthat is initially (i.e., before metal mesh expansion) in a load-bearingstate.

The above-mentioned mechanism (or means) employed by the above-mentionedsystems (of a second type) is afforded by annular obstruction devices(e.g., devices 124, 126, 130, and 134, as depicted in FIG. 1), whereinsuch devices are said to be coiled spring-based. This type of mechanismor means is mechanistically different from that employed in systems of afirst type that utilize a chamber-based annular obstruction mechanism.

With reference to FIGS. 5A, 5B, 6A, and 6B, and with continued referenceto FIG. 1 (for exemplary system component correlation), in someembodiments the present invention is directed to a system (or systems)for initiating annular obstruction in a subsurface well 110, said systemcomprising: (a) an at least partially permeable liner string 120(comprised of multiple liner joints or segments) situated within aportion of a wellbore (e.g., of subsurface well 110) that is at leastpartially open (e.g., region 184) to a hydrocarbon-bearing formation;(b) a load-bearing coiled spring (501, 601) disposed about a portion(e.g., a joint or pipe segment) of the at least partially permeableliner string 202, wherein the load-bearing coiled spring is in aload-bearing state selected from the group consisting of a tensionedstate (e.g., coiled spring 501) and a compressed state (e.g., coiledspring 601); (c) a spring retainer device (503, 603) attached to theload-bearing coiled spring so as to maintain it in a load-bearing state,wherein the spring retainer device is at least partially fabricated ofmaterial designed to melt (or otherwise lose its mechanical integrity)above a predetermined temperature, and wherein upon melting (e.g.,melted retainer devices 505 and 605) loses its ability to maintain thecoiled spring in a load-bearing state; and (d) metal mesh (506, 606)interposed with the load-bearing spring such that removal of the loadfrom the spring causes the metal mesh to engage the formation (alongopen borehole wall 123), thereby forming an annular obstruction (e.g.,124, 126, 130, and/or 134) between the liner string 120 and theformation (any of regions 125, 135, 145, and 155), wherein the loadremoval is effected by application of heat to the annular regionsufficient to melt at least a portion of the spring retainer device.

In some such above-described system embodiments, the subsurface well 110is a steam injection well. While such systems are directed to generatingannular obstruction/isolation in subsurface wells in general, steaminjection is a economical and efficient method for additionally serving(in addition to its primary enhanced oil recovery purpose) as a means ofheating, capable of melting the spring retainer device and effecting achange in the coiled spring from a load-bearing state to anon-load-bearing state, and thereby causing the metal mesh to engage theformation so as to provide annular obstruction (vide infra).

In some such above-described system embodiments, the well 110 is adeviated well, or at least includes sections that are deviated fromvertical (i.e., the vertical axis made with the plane of the surface).The well of FIG. 1, i.e., subsurface well 110, is depicted as a deviatedwell, wherein a significant portion of the open hole region of the wellruns in a substantially horizontal direction through much of theformation. Such horizontal wells are common in steam flooding activitiesfor enhanced oil recovery.

In some such above-described system embodiments, the at least partiallypermeable liner string comprises pores of a type selected from the groupconsisting of pre-drilled holes, slots, screens, and combinationsthereof. In FIG. 1, liner string 120 comprises pores 128, 142 depictedas pre-drilled holes. The term, “pore,” as used herein, is notparticularly limiting, and can be deemed to be an orifice or, moregenerally, an opening.

In some such above-described system embodiments, the coiled spring istensioned with a load of at least about 50 lb_(f) (pound-force) (222 N)(e.g., tensioned coiled spring 501, as shown in FIG. 5A). In someadditional or alternative such system embodiments, the coiled spring iscompressed with a load of at least about 50 lb_(f) (222 N) (e.g.,compressed coiled spring 601, as shown in FIG. 6A). Note that the natureof the load (tension or compression) can have implications for themanner in which the metal mesh is functionally-associated with theload-bearing coiled spring (vide infra).

In some such above-described system embodiments, the spring retainerdevice (e.g., 503, 603) is attached to at least one end of theload-bearing coiled spring. Wherein the spring retainer device anchorsonly a single end of the load-bearing coiled spring, it is contemplatedthat in such embodiments, the other end is affixed or made to otherwiseadhere to the liner string about which it is disposed (such embodimentsare depicted in FIGS. 5 and 6). In some or other embodiments, both endsof the load-bearing coiled spring are anchored to the liner string viameltable spring retainer devices, wherein the coiled spring floatsfreely about the liner string upon removal of the load.

Generally, the spring retainer device of the above-described systemembodiments should respond to thermal energy in such a manner that atsome particular temperature, the mechanical integrity of the device (ora portion thereof) is compromised in such a way as to render the deviceincapable of retaining the coiled spring in a load-bearing state,wherein the loss of mechanical integrity of the spring retainer deviceis thermally-induced. In some such above-described system embodiments,at least the meltable portion of the spring retainer device isfabricated of a thermoplastic polymeric material, i.e., a plasticmaterial with a glass transition temperature (as opposed to a thermosetmaterial that merely decomposes) that “melts” at a particulartemperature or over a particular range of temperatures. Suitable suchthermoplastic polymeric material can include, but is not limited to,polyethylene, polypropylene, acrylic, polyvinylidene chloride, blendsand combinations thereof, and the like.

In some such above-described system embodiments, the metal meshcomprises a woven metal mesh. In some or other such embodiments, themetal mesh comprises a sintered metal mesh. In some or other suchembodiments, the metal mesh comprises rolled metal fibers. In some orstill other embodiments, the metal mesh may be impregnated withmaterials such as, for example, thermosetting polymers, such materialsbeing operable for enhancing the annular obstruction. The metal mesh canbe of a variety of gauges, but it is preferable that the gauge be chosenwith consideration given to the coiled spring characteristics so thatthey can operate in optimal concert to effectively induce annularobstruction. Additionally, in some or other such embodiments, aprotective covering can be utilized to prevent damage to the metal meshwhile it is being deployed in the well. A suitable such covering may becomprised of a thermoplastic material.

Similar to systems of a first type, in some such above-described systemembodiments (i.e., systems of a second type), the annular obstructionreduces flow in the annulus (or in at least one or more regions thereof)by at least about 20 percent to at most about 100 percent. In some othersuch embodiments, the annular obstruction reduces flow in the annulus byat least about 20 percent to at most about 90 percent. In some or stillother embodiments, the annular obstruction reduces flow in the annulusby at least about 40 percent to at most about 90 percent. While notintending to be bound by theory, complete annular obstruction (i.e.,annular isolation) is generally more difficult to achieve with thecoiled spring-based annular obstruction device(s) (that are generallypart of systems of a second type) than with the chamber-based devices ofsystems of a first type.

In some such above-described system embodiments, the heat applied to theannular region to melt the spring retainer device (or a portion thereof)is provided by the injection of a heated fluid into the well. In somesuch system embodiments, the heated fluid is steam—fortuitous in thecase of steam injection wells, in that the steam can serve a dualpurpose. Other heated fluids and/or heating means (e.g., chemical,radiative), on the surface and/or downhole, can be additionally oralternatively employed to melt the spring retainer device(s) mentionedabove.

In some such above-described system embodiments, such systems canfurther comprise one or more additional load-bearing springs, springretainer devices, and metal mesh, so as to effect multiple annularobstructions in the wellbore. Such an embodiment may be seen to beillustrated in FIG. 1, wherein four such annular obstruction devices(e.g., coiled spring-based such devices of systems/methods of a secondtype) are depicted in the figure as devices 124, 126, 130, and 134.

6. Methods of a Second Type

Method embodiments (of a second type) described in this sectiongenerally correspond in a substantial manner with the system embodiments(of a second type) described above in Section 5. Accordingly, referencewill continue to be made, in exemplary fashion, to FIGS. 1, 5A, 5B, 6A,and 6B, as many of the details are common to both the system and method.Generally, such methods make use of annular obstruction devices (e.g.,124, 126, 130, and 134, as depicted in FIG. 1) that employ a coiledspring mechanism, i.e., coiled spring-based annular obstruction devices.

Referring now to FIG. 7, in some embodiments, the present invention isdirected to a method for initiating annular obstruction in a subsurfacewell, said method comprising: (Step 701) fabricating an at leastpartially permeable length of modified liner string, the length ofmodified liner string comprising: (i) a load-bearing coiled springdisposed about at least a portion of the modified liner string, whereinthe load-bearing coiled spring is in a load-bearing state selected fromthe group consisting of a tensioned state and a compressed state; (ii) aspring retainer device attached to the load-bearing coiled spring so asto maintain it in the load-bearing state, wherein the spring retainerdevice is at least partially fabricated of material designed to meltabove a predetermined temperature, and wherein upon melting loses itsability to maintain the coiled spring in a load-bearing state; and (iii)metal mesh interposed with the load-bearing coiled spring such that whenthe coiled spring undergoes a transformation from a load-bearing stateto a non-load-bearing state, the metal mesh expands outward in a radialdirection; (Step 702) positioning the modified length of modified linerstring in an open hole region of a wellbore, wherein an annular regionis established between the modified length of liner string and the openhole region of the wellbore; and (Step 703) heating the modified lengthof liner string so as to melt the spring retainer device and effect thetransformation of the coiled spring to the non-load-bearing state,correspondingly causing the metal mesh to expand outwardly and engagethe formation, thereby forming an annular obstruction between themodified length of liner string and the open hole.

As in the case of the analogous system embodiments (of a second type)described above, in some such above-described method embodiments (of asecond type), the subsurface well is a steam injection well. In somesuch embodiments, the steam injected into the subsurface (in an effortto enhance oil recovery) can further serve as a means by which themodified length of liner string can be heated so as to effect themelting of (or loss of integrity in) the spring retainer device, whichin turn effects the transition of the coiled spring from a load-bearingstate to a non-load-bearing state.

Corresponding to the analogous system embodiments described in Section 5above, in some such above-described method embodiments, the subsurfacewell is a deviated well. Generally speaking, a well is deemed to be“deviated” if a substantial part of the wellbore deviates from avertical axis established with the surface. Note that such deviation istypically intentional (e.g., directional drilling); and while some suchsubsurface wells so formed are largely horizontal (common for steaminjection wells), the wells used in conjunction with at least somemethods and/or system embodiments of the present invention are notrequired to be of the deviated variety.

Corresponding to the analogous system embodiments above, in some suchabove-described method embodiments (i.e., of a second type), the atleast partially permeable liner string comprises pores (openings) of atype selected from the group consisting of pre-drilled holes, slots,screens, and combinations thereof. Characterization and variation amongsuch pores is as described above in the analogous system embodiments.

In some such above-described method embodiments (of a second type), theload-bearing coiled spring is tensioned with a load of at least 50lb_(f) (222 N). In other such above-described method embodiments, theload-bearing coiled spring is compressed with a load of at least 50lb_(f) (222 N). In either case (tensioned or compressed), in some suchembodiments the load imparted to the spring may well dictate the typeand characteristics of the coiled spring so employed (or vice versa).Additionally, in some embodiments, the type and characteristics of thecoiled spring may well dictate the type and characteristics of the metalmesh used in combination with the coiled spring, wherein a synergisticbalance is desired so as to effect optimal annular obstruction (videinfra).

In some such above-described method embodiments, the spring retainerdevice (503, 603) is attached to at least one end of the load-bearingcoiled spring. Wherein the spring retainer device anchors only a singleend of the load-bearing coiled spring, it is contemplated that in suchembodiments, the other end is affixed or made to otherwise adhere to theliner string about which it is disposed (such embodiments are depictedin FIGS. 5 and 6. In some or other embodiments, both ends of theload-bearing coiled spring are anchored to the liner string via meltablespring retainer devices, wherein the coiled spring free-floats about theliner string subsequent to load removal.

Generally, the spring retainer device of the above-described methodembodiments should respond to heat (i.e., thermal energy) in such amanner that at some particular temperature (or particular range oftemperatures), the mechanical integrity of the device (or a portionthereof) is compromised in such a way as to render the device incapableof retaining (or maintaining) the coiled spring in a load-bearing state,wherein the loss of mechanical integrity of the spring retainer deviceis thermally-induced. In some such above-described method embodiments,at least the meltable portion of the spring retainer device isfabricated of a thermoplastic (“meltable”) polymeric material, i.e., aplastic material with a glass transition temperature (as opposed to athermoset material that merely decomposes). Suitable such thermoplasticpolymeric material can include, but is not limited to, polyethylene,polypropylene, acrylic, polyvinylidene chloride, blends and combinationsthereof, and the like.

In some such above-described method embodiments, the metal meshcomprises a woven metal mesh. In some or other such embodiments, themetal mesh comprises a sintered metal mesh. In some or other suchembodiments, the metal mesh comprises rolled metal fibers. In some orstill other embodiments, the metal mesh may be impregnated withmaterials such as, for example, thermosetting polymers, such materialsbeing operable for enhancing the annular obstruction. The metal mesh canbe of a variety of gauges, but it is preferable that the gauge be chosenwith consideration given to the coiled spring characteristics so thatthey can operate in optimal concert to effectively induce annularobstruction. Additionally, in some or other such embodiments, aprotective covering can be utilized to prevent damage to the metal meshwhile it is being deployed in the well. A suitable such covering may becomprised of a thermoplastic material.

In some such above-described method embodiments, the annular obstructionreduces flow in at least some regions of the annulus from at least about20 percent to at most about 100 percent, i.e., complete annularobstruction or isolation for one or more annular regions. In some orother such embodiments, the annular obstruction reduces flow in suchannular regions from at least about 40 percent to at most about 100percent.

As mentioned above for the corresponding system embodiments (of a secondtype), and while not intending to be bound by theory, complete annularobstruction (i.e., annular isolation) is likely to be less frequentlyachieved using the coiled spring-based annular obstruction device(s) ofmethods of the second type—in relation to methods of a first typeutilizing chamber-based annular obstruction device(s).

In some such above-described method embodiments, the heat applied to theannular region to melt the spring retainer device is provided by steaminjection. Additional heating subsurface, with strategically-positionedheaters or other heating means, can impart additional control over thetemporal actuation of the annular obstruction device(s). As mentionedabove, particularly for the case of steam injection wells used forenhanced oil recovery, in some such method embodiments the means ofheating the condensed material involves injecting steam into the well.

In some such above-described method embodiments, the application of heat(i.e., heating) makes use of conventional heating means known to personsskilled in the art. In some or other method embodiments, such heatingmeans can additionally or alternatively make use of radiative heatingmeans (e.g., microwave or radiofrequency (RF) heating) and/or chemicalheating means (e.g., an exothermic chemical reaction).

In some such above-described method embodiments (of a second type), suchmethods further comprise the use of multiple modified lengths ofmodified liner string, as multiple joints within an overall liner stringassembly, so as to effect multiple annular obstructions in multipleregions of the wellbore. An exemplary such embodiment is shown in FIG.1, where four such annular obstruction devices (124, 126, 130, and 134)are shown.

7. Variations

Variational embodiments of the above-described systems and methodsinclude systems and/or methods of a first type incorporating elements ofsystems and/or methods of a second type (or vice versa). For example,and with reference to the exemplary system configuration of FIG. 1,annular obstruction devices 124 and 126 could be based on the sealedmetal chamber (systems/methods of a first type), whereas annularobstruction devices 130 and 134 could be based on the coiled spring(systems/methods of a second type). Such embodiments are deemed hybridsystems (with corresponding hybrid methods) of the present invention forinducing annular obstruction in a subsurface well.

Variational embodiments also include systems and methods incorporating aplurality of any of the above-described annular obstruction devices(chamber- and/or coiled spring-based) that are designed or engineered toactuate at different temperatures. Proper such design can be seen tosignificantly advance the extent to which such a system can becontrolled via “hybrid” means (vide supra).

Other presently-contemplated variations include, but are not limited to,the use of different heating means and/or different heating fluidswithin the same well, the former with different types of systems (i.e.,hybrid systems), and either or both of the former used together togenerate a super system comprising a plurality of any of such systems ina plurality of such wells to stimulate hydrocarbon resources in a commonreservoir. Additionally or alternatively, any of such systems can beused in subsurface wells other than previously described and/or incollective or concerted fashion among two or more wells of differingtype.

8. Summary

As described throughout, the present invention is directed to systemsand methods for initiating annular obstructions in subsurface wellslargely used in, or in support of, enhanced oil recoveryoperations—particularly enhanced oil recovery efforts involving steaminjection (e.g., steam flooding). In at least some instances, system andmethod embodiments of the present invention utilize one or morepassively-activated/actuated devices (or hybrid variants thereof) forinducing annular obstruction, wherein the associated passiveactivation/actuation is at least partially controlled by thermal meanssuch that it can be deemed to be thermally-directed. Suchthermally-directed passive activation can afford considerably morecontrol over the annular obstruction process (hence the term, “hybridactivation/actuation”) and, correspondingly, over the overall steaminjection into the formation and associated reservoir—thereby providingmore efficient recovery.

All patents and publications referenced herein are hereby incorporatedby reference to the extent not inconsistent herewith. It will beunderstood that certain of the above-described structures, functions,and operations of the above-described embodiments are not necessary topractice the present invention and are included in the descriptionsimply for completeness of an exemplary embodiment or embodiments. Inaddition, it will be understood that specific structures, functions, andoperations set forth in the above-described referenced patents andpublications can be practiced in conjunction with the present invention,but they are not essential to its practice. It is therefore to beunderstood that the invention may be practiced otherwise than asspecifically described without actually departing from the spirit andscope of the present invention as defined by the appended claims.

1. A system for initiating annular obstruction in a subsurface well,said system comprising: a) an at least partially permeable liner stringsituated within a portion of a wellbore that is at least partially opento a hydrocarbon-bearing formation; b) a sealed metal chamber disposedabout a portion of the at least partially permeable liner string; c) amaterial contained within the sealed metal chamber, wherein saidmaterial is initially in a condensed state, but which transitions to agaseous state when heated above a certain threshold temperature; and d)a means of heating the material contained within the metal chamber so asto effect its transition to the gaseous state where, upon transitioningto a gas, the material increases the pressure within the chamber, andwhere, upon experiencing a pressure increase, the metal chamber expandsin such a way as to engage the formation, thereby forming an annularobstruction between the at least partially permeable liner string andthe formation.
 2. The system of claim 1, wherein the subsurface well isa steam injection well for initiating annular obstruction in asubsurface well.
 3. The system of claim 1, wherein the at leastpartially permeable liner string comprises pores of a type selected fromthe group consisting of pre-drilled holes, slots, screens, andcombinations thereof.
 4. The system of claim 1, wherein the sealed metalchamber is selected from the group consisting of: a) an integral part ofthe liner pipe making up at least part of the at least partiallypermeable liner string, or b) an attachment affixed to the at leastpartially permeable liner string.
 5. The system of claim 1, wherein thesealed metal chamber has a geometry configured to enhance its ability toengage the formation upon expanding.
 6. The system of claim 1, whereinthe sealed metal chamber comprises at least one relief valve designed tovent below the burst pressure of said chamber.
 7. The system of claim 1,wherein the sealed metal chamber comprises a volume, in the unexpandedstate, of from at least about 50 cubic inches to at most about 12,000cubic inches; and wherein the material inside the sealed metal chamber,upon transitioning to a gaseous state, increases the volume of thesealed metal chamber by at least 50 percent.
 8. The system of claim 1,wherein the material inside the sealed metal chamber is, in itscondensed state, in a form selected from the group consisting of liquid,solid, and any mixture thereof; and wherein the material inside thesealed metal chamber is selected from the group consisting of water,alcohols, glycols, glycerine, acrylic, polyvinylidene, and combinationsthereof.
 9. The system of claim 1, wherein the annular obstructionreduces flow in the annulus by at least about 20 percent to at mostabout 100 percent.
 10. The system of claim 1, wherein the means ofheating the condensed material comprises introduction of a downhole heatsource.
 11. The system of claim 1, wherein the meaning of heatinginvolves injection of a heated fluid into the well.
 12. The system ofclaim 11, wherein the means of heating the condensed material involvesthe injection of steam into the well.
 13. The system of claim 1, furthercomprising one or more additional sealed metal chambers filled with thecondensed material, so as to effect multiple annular obstructions in thewellbore.
 14. A method for initiating annular obstruction in asubsurface well, said method comprising: a) fabricating a modifiedlength of at least partially permeable liner string, the modified lengthcomprising: i) a sealed metal chamber disposed about the modified lengthof at least partially permeable liner string; and ii) a materialsituated inside the sealed metal chamber, wherein said material isinitially in a condensed state and which transitions to a gas whenheated above a certain threshold temperature; b) positioning themodified length of at least partially permeable liner string in an atleast partially open hole region of a wellbore, wherein an annularregion is established between the modified length of permeable linerstring and the open hole region of the wellbore; and c) heating themodified length of liner string so as to effect a transition of thematerial contained therein from a condensed state to a gaseous state,where upon transitioning to a gas, the material increases the pressurewithin the sealed metal chamber, and where upon experiencing a pressureincrease the sealed metal chamber expands in such a way as to engage theformation, thereby forming an annular obstruction between the modifiedlength of liner string and the formation.
 15. The method of claim 14,wherein the subsurface well is a steam injection well.
 16. The method ofclaim 14, wherein the at least partially permeable liner stringcomprises pores of a type selected from the group consisting ofpre-drilled holes, slots, screens, and combinations thereof.
 17. Themethod of claim 14, wherein the sealed metal chamber is selected fromthe group consisting of: a) an integral part of the liner pipe making upat least part of the at least partially permeable liner string, or b) anattachment affixed to the at least partially permeable liner string. 18.The method of claim 14, wherein the sealed metal chamber has a geometryconfigured so as to enhance its ability to engage the formation uponexpanding.
 19. The method of claim 14, wherein the sealed metal chambercomprises at least one relief valve designed to vent below the burstpressure of said chamber.
 20. The method of claim 14, wherein the sealedmetal chamber comprises a volume, in the unexpanded state, of from atleast about 50 cubic inches to at most about 12,000 cubic inches; andwherein the sealed metal chamber, upon transitioning to a gaseous state,increases the volume of the sealed metal chamber by at least 50 percent.21. The method of claim 14, wherein the material situated inside thesealed metal chamber is, in its condensed state, in a form selected fromthe group consisting of liquid, solid, and any mixture thereof; andwherein the material situated inside the sealed metal chamber isselected from the group consisting of water, alcohols, glycols,glycerin, phase change materials, eutectics, and combinations thereof.22. The method of claim 14, wherein the annular obstruction reduces flowin the annulus from at least about 20 percent to at most about 100percent.
 23. The method of claim 14, wherein the means of heating thecondensed material involves injection of a heated fluid into the well.24. The method of claim 23, wherein the means of heating the condensedmaterial involves injecting steam into the well.
 25. The method of claim14, further comprising the use of multiple modified lengths of at leastpartially permeable liner string, so as to effect multiple annularobstructions in multiple regions of the wellbore.